nested

If you read my blog, you’ve probably noticed I’ve been doing a lot of stuff with hypervisors lately, more specifically setting up OpenStack. I’ve always been a VMware guy. I like the simplicity of ESXi and the intuitiveness of of the interface. Since OpenStack really works best with at least 3 servers, 2 of which don’t do much of anything, I decided to use an ESXi server to install the openstack infrastructure. The controller node and network node do not provide any type of virtualization capabilities, but the compute node(s) do.

ESXi, at least since version 5.1, has supported running 64-bit hypervisor guests, or “nested” hypervisors on any Intel i3 or newer CPU. Specfically, your CPU needs to be one of the following:

Intel VT-x or AMD-V for 32-bit nested virtualization

Intel EPT or AMD RVI for 64-bit nested virtualizaiton

In my case, my Xeon W5580 has VT-x and EPT support, so I can run 64-bit nested virtual machines.

This will allow you to run any nested hypervisor within an ESXi 5.1 or newer host. I’ve ran Xen, KVM, OpenStack, Proxmox, and ESXi; they all worked great.

How To Enable

The feature, or setting, of the virtual machine that allows the VT-x functionality to be passed through to the guest virtual machine is called HV (as in hypervisor). The problem is you have to be running the new vSphere Web Client to get at the nice little check box to turn this on. The vSphere Desktop Client does not have this functionality and unless you have a license for vSphere server, there is no way to enable HV on a virtual machine using the GUI. However, there is a VERY easy work around for this. You simply add a single line to the .vmx file for the virtual machine you need HV enabled on.

To do this, fire up the vSphere Client, and make sure the host is selected in the left pane. Also, verify the VM is powered OFF.